Hioki 3532-50 LCR Repair (One major problem solved, SM still wanted)

[TERRA Operative]

I found a Japanese user manual for sale here on Yahoo Auctions, but it's not the service manual... It's the same one in my google drive link above.

At least it shows that manuals are being sold, so I'll keep an eye out, we might find a service manual one day...........

[Martin72]

No response from the hioki distributor so far, next week I´ll order the touchpanel from the (far east) ebay-seller.
The 5V LDO is on it´s way and I think I exchange the bnc sockets too, as they´re a little bit "rusty" looking.
Finally clean the contacts of the display and then....Test if the display light is ok.
(you must turn it on/off in the menu, the menu I can use when the new touchpanel is assembled)
That all could last some weeks...
But it will be surely worth it.

[Martin72]

No response from the hioki distributor so far

No good news from them...
Production ended in 2015, service support ended in 2021.
This means that since that date there is nothing more for it, no spare parts and no documents like the service manual.
That, in turn, was only available for authorized service workshops.
Fortunately, the device does not have an electrical defect in the sense that it requires the manual.
But maybe I'll be lucky someday and get it after all.
Now I want to order the panel from the Ebay seller, but he is on "vacation" until February.

[TERRA Operative]

Might have to get friendly with a tech at a service center or two...

[mawyatt]

Are you sure you want to change the BNC connectors? Would think this might have an effect on the calibration, and without a cal manual, and the necessary cal standards, might not be a good idea!! Sure you may not know the cal state of the instrument as is, but changing the connectors seems it will just increase the uncertainty, altho look nicer.

After you get the LDO and new front panel installed, maybe just clean the connectors as best you can for starters. BTW the original panel after you cleaned/processed it doesn't seem too bad IMO!!

Best,

[Martin72]

Tadaa....
Arrived today:

[Finity]

Any updates on this project? Have the lesser 3522-50, and the screen, while still functional, has a few areas that take pressing twice before responding. Also, is the new screen less yellow than the aged screens for better contrast? Would consider upgrading if so. Nice project!

[Martin72]

Hi !
It's a shame but I didn't reassemble the unit so far...
Will do it in the next weeks..

[Martin72]

In the next days...

[Martin72]

Hi,

Today I assembled the new touchpanel.
After some "modifications" it works fine. 
But...
I´m afraid I need a new display.
The Backlight is dead, it have some blank stripes and after a while, it "fades" off.
Well...There two choices.
New and Replacement:

https://www.elecok.com/de/pg320240c-lcd-panel-replacement.html?origin=recent

Or "original" (but new??):

https://www.elecok.com/de/pg320240c-lcd-panel-original.html?origin=recent

A decision of appx 160€ difference..

[Martin72]

A service manual would be sooo helpful....
When I had completely disassembled the front panel, I had unfortunately not taken any pictures of it and am currently puzzling over how what belongs back together.
This complicates things a bit.
I can't understand it, the support is completely stopped, there are no spare parts anymore, absolutely zero, the corresponding service partners can't do any repairs anymore - But the documents remain under lock and key...
Should everyone throw away his once expensive device when it is broken ?!
Anyway, it will go on, just slower without the service manual.

[TERRA Operative]

If it's a bad backlight, that's at least repairable. Maybe some LED's or a CCFL tube?

If the problem is in the actual pixels, maybe you can open up the LCD assembly and clean the zebra strips if they are used?

[Martin72]

Hi!

Maybe some LED's or a CCFL tube?

This powertip pg320240C display got a tiny CCFL tube, onboard of the hioki there´s an inverter for it.
If I would buy the display substitute, this will come with a LED backlight.
No greater problem, I would deactivate the inverter circuit and take the on/off signal for the LED backlight instead.
The blank stripes could be indeed eliminated by cleaning the zebrastripes - but the other thing, that the whole display fade away...After turning off/on, it´s back again - And fade away after a while..Or it is a kind of adjustment in the menu - Before I´ve played a lot in it to test the new touchpanel...RTFM I guess.


Martin

[TERRA Operative]

That fading over time, I would look at the contrast control circuitry. I know the Tek TDS200 scopes have a 50K thermistor after the contrast control signal from the MCU (that is referenced to a TL431) to help counteract temperature drift in the LCD.

Also, you could maybe try the ol' LED conversion with some thin LED strip?
I have a bunch of this stuff that I have used to great success in my Tek THS720 scopes, and might have a go at using it in my TDS220 scope too. I can send you a piece for the cost of shipping once I'm back from holiday in a week or so if you like.

https://www.aliexpress.com/item/4000912596869.html

[Martin72]

Hi,

And fade away after a while..Or it is a kind of adjustment in the menu - Before I´ve played a lot in it to test the new touchpanel...RTFM I guess

Exactly that...
When I was playing around with the touch panel, I must have hit the LCD on/off function.
When on "off", the display turns off after about 10sec...Goes back on when you touch something somewhere on the field...Arghh.

[Martin72]

Hi,

Today I assembled the new touchpanel.
After some "modifications" it works fine. 

This panel is absolute crap, not worth the money...
The contacts are so porous that they virtually dissolve after one or two times.
What had previously worked via touch, now no longer works, only a few fields.
So much money for such a crap....
Maybe I'll manage to fix it.
But I would prefer a completely new solution for the touch panel and display.

[coromonadalix]